I used those exact connectors last night to wire my reverse lights on my bumper. Definitely using the right size will help. Also, use a heat gun, it will shrink quick and nice. I've tried a blow dryer and it just doesn't shrink as nice. Ill post up some pics in my thread todayI found the heat shrink wire connectors difficult to work with. In particular, crimping the inside metal to hold the wire tight. I screwed up a few because I would crimp and not catch the wire tightly.